EP-A-0909809 discloses a class of iron coordination complexes useful as catalysts for the bleach activation of peroxy compounds, including iron complexes comprising the ligand N,N-bis(pyridin-2-yl-methyl)-1,1-bis(pyridin-2-yl)-1-aminoethane, also referred to as MeN4Py. These catalysts are said to be useful in bleaching systems comprising a peroxy compound or a precursor thereof, such as in the washing and bleaching of substrates including laundry, dishwashing and hard surface cleaning, or for bleaching in the textile, paper and woodpulp industries, and in waste water treatment.
In our co-pending application PCT/GB99/02876, we describe methods for catalytically bleaching substrates with atmospheric oxygen in aqueous medium, using metal ligand complexes as catalytic bleaching agents. These methods are said to be particularly applicable to bleaching of laundry fabrics, suitably in detergent formulations, but also may be used for hard surface cleaning, waste-water treatment, pulp bleaching in paper manufacture, leather manufacture, dye transfer inhibition, food processing, starch bleaching, sterilisation, whitening in oral hygiene preparations and/or contact lens disinfection.
However, there remains a need for improved methods of bleaching stained laundry fabrics. Thus, it would be desirable to be able to effect improved bleaching of particular stain types. It would also be desirable to be able to bleach a broader profile of stain types more effectively.